This disclosure relates generally to online systems, and more specifically to selecting content for presentation to users of an online system.
An online system allows its users to connect and communicate with other online system users. Users create profiles on the online system that are tied to their identities and include information about the users, such as interests and demographic information. The users may be individuals or entities such as corporations or charities. Because of the popularity of online systems and the significant amount of user-specific information maintained by online systems, an online system is in a unique position to leverage information in its possession to select content for presentation to its users that is likely to be relevant to the users. For example, if a user has provided profile information indicating that the user has an interest in restoring classic cars, the online system may select a content item including an image of a restored classic car for presentation to the user based on the user's profile information and information stored in association with the content item indicating its contents. Content items are selected for presentation to various users by the online system to encourage users to interact with the online system. By increasing user engagement with the online system, the online system also increases the number of opportunities it has to generate revenue (e.g., by presenting advertisements to its users).
Conventionally, online systems select content items for presentation to online system users based on targeting criteria associated with content items identifying characteristics of online system users who are eligible to be presented with the content items. For example, if a content item is associated with targeting criteria identifying one or more characteristics of users who are eligible to be presented with the content item, the online system identifies users of the online system having at least a threshold number of the characteristics identified by the targeting criteria as eligible to be presented with the content item and does not present the content item to users that do not have at least the threshold number of characteristics specified by the targeting criteria. User characteristics specified by targeting criteria may include information associated with individual users, such as demographic information, connections between users and other users, actions performed by a user, interests of the user, etc.
However, targeting criteria associated with content items typically do not account for the fact that the relevance of content items to users may change when the users form a group that has gathered for a particular purpose, at a particular time and location. For example, a user that works full-time and never watches movies alone is much more likely to find an advertisement for a new movie to be relevant when the user is meeting with a group of friends near a movie theater on a weekend. Thus, conventional online systems may present content items to users that are not relevant or may miss opportunities to present relevant content items to users due to their failure to account for changes in the relevance of content items to users in group settings.